The family of a South San Francisco teenager who was shot and killed by police at a gas station filed a federal lawsuit Tuesday, alleging the fatal shooting was the result of unlawful racial profiling by officers.

Derrick Gaines, 15, was killed June 5 after he and a 14-year-old friend were stopped by police as they walked through an Arco gas station on the 2300 block of Westborough Boulevard around 8:45 p.m.

South San Francisco police said they questioned the two boys because they were engaged in suspicious behavior. Gaines was African American and his friend is Filipino.

According to the lawsuit, which seeks $10 million in damages, Gaines initially answered questions from officers and then ran for about 20 feet before he was tripped by the pursuing officer, Joshua Cabillo.

Attorneys for Gaines' family acknowledged that a handgun fell from the teenager's waistband during the ensuing tussle, but say Cabillo overstepped his authority when he fired the two shots that killed Gaines.

Police said Cabillo, who was cleared of wrongdoing by the San Mateo County district attorney after an investigation in August, fired only after Gaines pointed the gun at him.

John Burris, the Gaines family attorney, said officers did not have a reasonable cause to make contact with Gaines and his friend.

"But for racial profiling this young man would still be alive," Burris said.